In general, there are an active method and a passive method as methods for measuring a distance and angle of a target using an acoustic signal. The active method emits a particular sound wave toward a target and measures the time of a reflective wave returning from the target, to thereby calculate a distance and angle with respect to the target. The passive method measures a distance and angle of a sound source relying upon an acoustic signal emitted from the sound source.
Here, as the passive methods, there have been proposed a method for estimating an angle using a number of directional microphones as in Korean patent laid-open publication 90-5252, a method for measuring only an angle using more than two or three sensors as in U.S. Pat. Nos. 3,947,803, 4,245,430, and 4,601,025, and a method for measuring an angle and distance using three or more sensors as in U.S. Pat. Nos. 4,317,186, 4,910,719 and 5,586,086.
First, in view of arrangement of sensors, since a number of sensors are used in matrix in U.S. Pat. No. 4,317,186, and three sensors are aligned in line in U.S. Pat. No. 4,910,719, the distance and angle of the sound source can be measured only within 180 degrees, and since movement of an acoustic source is tracked to calculate a point of generation of an acoustic signal in U.S. Pat. No. 5,586,086, various other problems are revealed.
Then, in view of processing of acoustic signals, an electrical signal of a sound wave received in each channel is rectified and converted into an acoustic energy and then a peak point is detected and an arrival delay time of the waveform detected in each channel is measured, to thereby obtain an angle and distance of the sound source, in U.S. Pat. Nos. 3,947,803, 4,245,430, 4,717,364 and 5,407,376.
Thus, in these measuring methods, a loss and error of time may occur in a rectification process of a sound signal and a peak value detection process. Also, since a high speed measuring for real-time processing does not facilitate, a number of samples cannot be extracted within a short time and thus a correction of a measuring error is limited to thereby lower an accuracy of measurement.
Meanwhile, in view of an operating toy, only a direction of a sound source which generates a sound is recognized in Korean patent laid-open publication 90-5252 and U.S. Pat. No. 4,245,430, so that the operating toy operates in reply to the acoustic signal. Thus, since the operating toy does not recognize a distance from the sound source and may proceed in the direction only for a time of generation of sound, a user should generate a sound continuously in the case that he or she tries to contact the operating toy.
Also, U.S. Pat. Nos. 4,717,364 and 5,647,787 disclose a user command recognition function and an operation for performing the user command. However, they perform an irrelevant operation to a user position.
As described above, the prior art has not proposed a method for obtaining an angle and distance with respect to a sound source in a two-dimensional and/or three-dimensional space at high speed in real time, and correcting a measuring error by using the angle and distance, to thereby not heighten an accuracy of measurement.
Further, the prior art has not proposed an intelligent and interactive operating toy capable of recognizing an angle and distance with respect to a sound source, for example, a user and tracking the user in reply to a call or command of the user, and performing an operation based on the recognized command.